Project inputs
Fields marked with matter most.Formula used
This calculator estimates permitting and approval costs by summing fee components and adding overhead, contingency, discounts, and optional tax. Complexity multipliers adjust plan review effort for roof and mounting types.
| Permit core | permit_core = base_permit + (per_kw_fee × system_kw) |
|---|---|
| Plan review | plan_review = (plan_review_pct/100) × permit_core × roof_mult × mount_mult |
| Inspections | inspection_total = inspection_visits × inspection_fee_each |
| Subtotal | subtotal_before_overhead = core_fees + external_fees + optional_services |
| Overhead | admin_overhead = (admin_overhead_pct/100) × subtotal_before_overhead |
| Contingency | contingency = (contingency_pct/100) × (subtotal_before_overhead + admin_overhead) |
| Grand total | grand_total = max(0, pre_tax_total + tax) |
How to use this calculator
- Enter your project name, jurisdiction, currency, and system size.
- Fill in permit fees from your authority’s published schedule.
- Add inspection visits and per‑visit inspection charges.
- Include utility, HOA, and optional service items if applicable.
- Set overhead and contingency based on your internal process.
- Press Calculate to see totals above the form.
Permitting cost drivers in solar projects
Solar permit budgets are shaped by local authority fee schedules, system size charges, and the level of technical review required. A flat base fee often covers intake, record creation, and issuance. Variable fees frequently scale by kilowatt, valuation, or equipment count, which is why the calculator starts with a permit core built from base and per‑kW inputs.
Plan review and structural scrutiny
Plan review is commonly billed as a percentage of permit value or as a published line item. Review effort rises when roofs are brittle, penetrations are numerous, or attachments demand additional calculations. The calculator applies modest roof and mounting multipliers to the plan review portion to reflect extra coordination for tile, flat roofs, ground mounts, and canopy structures.
Electrical permit and inspection workflow
Electrical permitting can be separate from building permits and may require dedicated diagrams, conductor sizing, and equipment listings. Inspections add time and cost through visit fees, travel, and rechecks. By entering the number of visits and fee per visit, you can model scenarios with combined finals versus staged rough and final inspections.
Utility interconnection and third‑party approvals
Interconnection applications may include standard processing fees, supplemental engineering review, and document revisions. Some sites also require homeowner association approvals, zoning clearance, or fire access verification. The calculator treats these as external fees so you can see how non‑permit items affect the overall approvals budget.
Overhead, contingency, and documentation controls
Administrative overhead captures filing, scheduling, site coordination, and communication cycles with reviewers. Contingency protects the budget against redesigns, missed inspection windows, and expedited processing. Track optional services such as engineering stamps and as‑built documentation to keep proposals consistent with deliverables, and export the breakdown for estimating reviews and client signoff. Because fee ordinances change, update inputs per project and capture the source in Notes. Run sensitivity checks by adjusting per‑kW fees, review percentages, and visit counts to understand best‑case and worst‑case permitting timelines and cash needs. early.
FAQs
1) What if my permit fee is valuation-based instead of per kW?
Enter the valuation-based amount as the base permit fee and set the per kW fee to zero. If plan review is a percent of valuation, use that published percentage for the plan review input.
2) Do the roof and mounting multipliers change every fee?
No. They only adjust the plan review portion to reflect added complexity. If your authority bills plan review as a fixed line item, tune the plan review percent so the result matches your invoice.
3) How should I model re-inspections or correction visits?
Increase the inspection visit count to include expected rechecks. If rechecks have a different fee, use a weighted average fee per visit or run two scenarios and compare totals.
4) Should utility interconnection be included in the permit budget?
Include it when your proposal covers end-to-end approvals. Enter the utility application charge under interconnection, and any supplemental engineering or review charges under utility review.
5) What overhead and contingency percentages are reasonable?
Overhead often ranges from 5–12% depending on travel and paperwork effort. Contingency is commonly 3–10% to cover revisions, rechecks, and schedule risk. Use your historical closeout data for best accuracy.
6) How can I share results with clients or estimators?
After calculating, use the CSV and PDF buttons in the results panel. Exports include project identifiers, key inputs, and the full line-item breakdown for transparent review and signoff.
Example data table
Use this example to understand typical inputs. Replace values with your local fees.
| Scenario | System (kW) | Base fee | Per kW | Plan review % | Visits | Visit fee |
|---|---|---|---|---|---|---|
| Small residential | 5.00 | $120.00 | $20.00 | 10% | 2 | $60.00 |
| Medium residential | 8.00 | $150.00 | $25.00 | 12% | 2 | $75.00 |
| Small commercial | 20.00 | $250.00 | $18.00 | 15% | 3 | $95.00 |
Notes on accuracy
- Use official fee schedules from your authority when possible.
- If your area uses valuation-based fees, model that as “base permit fee.”
- Expedite is estimated as a percent of permit core fees.
- For strict compliance, validate totals against your authority’s invoice.